Jack LaLanne, whose obsession with grueling workouts and good nutrition, complemented by a salesman’s gift, brought him recognition as the founder of the modern physical fitness movement, died Sunday afternoon at his home in Morro Bay, Calif. He was 96.

The cause was respiratory failure resulting from pneumonia, his family said.

A self-described emotional and physical wreck while growing up in the San Francisco area, Mr. LaLanne began turning his life around, as he often told it, after hearing a talk on proper diet when he was 15. H

e started working out with weights when they were an oddity, and in 1936 he opened the prototype for the fitness spas to come — a gym, juice bar and health food store — in an old office building in Oakland.

“People thought I was a charlatan and a nut,” he remembered. “The doctors were against me — they said that working out with weights would give people heart attacks and they would lose their sex drive.” But Mr. LaLanne persevered, and he found a national pulpit in the age of television.

“The Jack LaLanne Show” made its debut in 1951 as a local program in the San Francisco area, then went nationwide on daytime television in 1959. His short-sleeved jumpsuit showing off his impressive biceps, his props often limited to a broomstick, a chair and a rubber cord, Mr. LaLanne pranced through his exercise routines, most notably his fingertip push-ups.

He built an audience by first drawing in children who saw his white German shepherd, Happy, perform tricks.

“My show was so personal, I made it feel like you and I were the only ones there,” he told Knight-Ridder Newspapers in 1995. “And I’d say: ‘Boys and girls, come here. Uncle Jack wants to tell you something. You go get Mother or Daddy, Grandmother, Grandfather, whoever is in the house. You go get them, and you make sure they exercise with me.’ ”

His show continued into the mid-1980s.

“He was perfect for the intimacy of television,” Robert Thompson, a professor of television and popular culture at Syracuse University, told The San Jose Mercury News in 2004. “This guy had some of the same stuff that Oprah has and Johnny Carson had — the ability to insinuate themselves in the domestic space of people’s lives.”

Long before Richard Simmons and Jane Fonda and the Atkins diet, Mr. LaLanne was a national celebrity, preaching regular exercise and proper diet. Expanding on his television popularity, he opened dozens of fitness studios under his name, later licensing them to Bally. He invented the forerunners of modern exercise machines like leg-extension and pulley devices. He marketed a Power Juicer to blend raw vegetables and fruits and a Glamour Stretcher cord, and he sold exercise videos and fitness books. He invited women to join his health clubs and told the elderly and the disabled that they could exercise despite their limitations.

At 60 he swam from Alcatraz Island to Fisherman’s Wharf handcuffed, shackled and towing a 1,000-pound boat. At 70, handcuffed and shackled again, he towed 70 boats, carrying a total of 70 people, a mile and a half through Long Beach Harbor.

He ate two meals a day and shunned snacks.

Breakfast, following his morning workout, usually included several hard-boiled egg whites, a cup of broth, oatmeal with soy milk and seasonal fruit. For dinner he took his wife, Elaine, to restaurants that knew what he wanted: a salad with raw vegetables and egg whites along with fish — often salmon — and a mixture of red and white wine. He sometimes allowed himself a roast turkey sandwich, but never a cup of coffee.

Mr. LaLanne said he performed his exercises until he experienced “muscle fatigue,” lifting weights until it was impossible for him to continue. It produced results and, as he put it, “the ego in me” made the effort worthwhile.

The son of French immigrants, Jack LaLanne was born in San Francisco on Sept. 26, 1914, and spent his early years on his parents’ sheep farm in Bakersfield, Calif. By the time he was 15, the family having moved to the Bay Area, he was pimply and nearsighted, craved junk food and had dropped out of high school. That is when his mother took him to a women’s club for a talk by Paul C. Bragg, a well-known speaker on health and nutrition.

That talk, Mr. LaLanne often said, turned his life around. He began experimenting with weights at the Berkeley Y.M.C.A., tossed aside cakes and cookies and studied Gray’s Anatomy to learn about the body’s muscles. He graduated from a chiropractic school, but instead of practicing that profession he became a pitchman for good health.

He opened his first health studio when he was 21, and a decade and a half later he turned to television. He was first sponsored by the creator of a longevity pill, a 90-year-old man, but it sold poorly and he obtained Yami Yogurt as his new sponsor. “It tasted terrible, so I mixed it with prune juice and fruits,” he told The New York Times in 2004. “Nobody thought about it until then. We made the guy a millionaire.”

Mr. LaLanne, 5-foot-6 and 150 pounds or so with a 30-inch waist, maintained that he disliked working out. He said he kept at it strictly to feel fit and stay healthy. He built two gyms and a pool at his home in Morro Bay, and began each day, into his 90s, with two hours of workouts: weight lifting followed by a swim against an artificial current or in place, tied to a belt.

“The Jack LaLanne Show” may have run its course in the mid-1980s, but it had a second life in reruns on ESPN Classic. “We have over 3,000 shows,” Mr. LaLanne said in 2004. “I own everything.”

In September 2007, “Jack LaLanne Live!” made its debut on the online VoiceAmerica Health and Wellness Radio Network. He appeared on it with his wife and his nephew Chris LaLanne, a personal trainer.

In addition to his wife, Elaine, Mr. LaLanne is survived by their son, Jon, of Hawaii; his daughter, Yvonne LaLanne, of Walnut Creek, Calif., from his previous marriage, and a stepson, Dan Doyle, of Los Angeles, from Elaine LaLanne’s previous marriage.

Mr. LaLanne promoted himself and his calling into his final years, often accompanied at events by his wife, a physical fitness convert but hardly a fanatic. He brimmed with optimism and restated a host of aphorisms for an active and fit life.

“I can’t die,” he most famously liked to say. “It would ruin my image.”